effect-io-ai

Package: effect
Module: Effect

Effect.catchSomeDefect

Recovers from specific defects using a provided partial function.

Details

catchSomeDefect allows you to handle specific defects, which are unexpected errors that can cause the program to stop. It uses a partial function to catch only certain defects and ignores others. The function does not handle expected errors (such as those caused by fail) or interruptions in execution (like those caused by interrupt).

This function provides a way to handle certain types of defects while allowing others to propagate and cause failure in the program.

Note: There is no sensible way to recover from defects. This method should be used only at the boundary between Effect and an external system, to transmit information on a defect for diagnostic or explanatory purposes.

How the Partial Function Works

The function provided to catchSomeDefect acts as a filter and a handler for defects:

• It receives the defect as an input.
• If the defect matches a specific condition (e.g., a certain error type), the function returns an Option.some containing the recovery logic.
• If the defect does not match, the function returns Option.none, allowing the defect to propagate.

Example (Handling Specific Defects)

import { Effect, Cause, Option, Console } from "effect"

// Simulating a runtime error
const task = Effect.dieMessage("Boom!")

const program = Effect.catchSomeDefect(task, (defect) => {
  if (Cause.isIllegalArgumentException(defect)) {
    return Option.some(
      Console.log(
        `Caught an IllegalArgumentException defect: ${defect.message}`
      )
    )
  }
  return Option.none()
})

// Since we are only catching IllegalArgumentException
// we will get an Exit.Failure because we simulated a runtime error.
Effect.runPromiseExit(program).then(console.log)
// Output:
// {
//   _id: 'Exit',
//   _tag: 'Failure',
//   cause: {
//     _id: 'Cause',
//     _tag: 'Die',
//     defect: { _tag: 'RuntimeException' }
//   }
// }

Signature

declare const catchSomeDefect: { <A2, E2, R2>(pf: (defect: unknown) => Option.Option<Effect<A2, E2, R2>>): <A, E, R>(self: Effect<A, E, R>) => Effect<A2 | A, E2 | E, R2 | R>; <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, pf: (defect: unknown) => Option.Option<Effect<A2, E2, R2>>): Effect<A | A2, E | E2, R | R2>; }

Source

Since v2.0.0